After looking for inexpensive external antennae I came upon a great thread on Whirlpool describing how to make your own. I also wanted a better way to measure the signal strength while I point the dish, and found this page detailing the AT commands for the Optus/Huawei E169.
On a spare Sunday afternoon I put it all together, and to my surprise, it works exceptionally well!
With the dongle plugged into my computer I rarely get a 3G service. With this woktenna I get 4-5 bars of 3G. The best I've got is number 13 or -87dBm, a workable connection with 5 bars solid.
- One Mesh fruit bowl from Myers $30
- One Active USB cable (5m) from Jaycar $14.95
- One Paper Towel Holder from a bargain shop $2
- One beer coaster
- An old speaker mounting bracket
- Scraps of aluminium, bike parts and a drink bottle lid.
The focal point of the dish is 190^2/(4*105) = 85.95mm. This is just shy from the edge plane of the rim.
Here's a small ruby script that displays the signal strength directly from the Huawei E169. It requires
sudo gem install ruby-serialport
sp = SerialPort.new "/dev/tty.HUAWEIMobile-Modem", 38400
sp.read_timeout == 200
j1 = sp.readline
t = Time.new.to_s
puts "TIME: " + t + "SIGNAL: " + sp.readline